Chemical Properties

AdmireTM is a new insecticide developed
by Bayer and is available for use in Arizona for control of certain pests
in cotton, cole crops, lettuce, leafy greens, potatoes, and melons. AdmireTM is systemic and is highly active against aphids and
whiteflies when taken up by the plant's roots. AdmireTM's
common name is imidacloprid and was tested under the name NTN 33893. It
is formulated as a flowable and contains 2.0 lbs-active ingredient per
gallon of material.

AdmireTM belongs to a new class of
insecticide called the chlornicotynls. Its mode of action is unique from
any insecticides currently available for use in field crops and vegetables.
AdmireTM is a nicotine mimic and acts by binding to the nicotinic
receptor, thus simulating the action of acetylcholine. This action results
is continual stimulation of the nerve cells and eventual death of the
insect.

AdmireTM is very sensitive to ultra-violet
light and has a half-life of about four hours in direct sunlight. Thus
it should be applied soon after mixing. AdmireTM
undergoes microbial degradation in the soil and has a soil half-life of
<150 days. In the soil, it is not very mobile, particularly in heavy
soils with high cation exchange capacities.

Lettuces and Cole Crops

AdmireTM is recommended for use in
head and leaf lettuce, mustard, collards and cole crops for control of
sweetpotato whitefly (strain-B), Bemisia tabaci and aphids. AdmireTM
can be applied to these crops at 10 to 24 fluid ounces per acre. Application
techniques labelled include: sub-seed furrow injection, in-furrow spray,
transplant injection, soil-surface band, sidedress, post-seeding or pre-transplant
drench, or through drip or trickle irrigation systems. Research at The
University of Arizona has demonstrated that optimal performance of AdmireTM greatly depends on placement at the soil-root interface.
The key to obtaining successful performance with AdmireTM
is to place the product where it will stay in an aqueous solution within
the root zone of the plant. For lettuces and cole crops there are
three techniques that have demonstrated good efficacy for AdmireTM
with minimal mechanical crop damage. Although lettuce and cole crops differ
in root morphology, both crop types tend to concentrate their root mass
within the frame area of the plant. Sub-seed furrow applications of AdmireTM have been shown to be very effective when injected
into the soil 1.5 to 3.0 inches below the seed line just prior to planting
(Figure 1).

Figure 1. Proper placement of AdmireTM1.5-
3.0 inches
below the seed line in the moisture area of the root zone.

For transplanted cauliflower, AdmireTM
has demonstrated efficacy when injected into the soil into or just below
the zone where the transplant plug will be placed and the cauliflower's
roots will be concentrated. Soil-surface banded applications of AdmireTM have been shown to be extremely effective on direct-seeded
lettuce. Applications should be applied as a 2.0 to 3.0 inch band over
each seed line preemergence to the crop. The material should be hydrologically
incorporated within 24 hours of application using overhead sprinkler irrigation.
University research has shown that soil-surface banded applications that
were not incorporated with sprinkler irrigation but irrigated via furrow
irrigation did not provide adequate efficacy.

Side-dress applications of AdmireTM
to spring lettuces have given inconsistent aphid control in university
trials. Most of the problems with side-dress applications are associated
with placing the material within the root zone without pruning the roots,
or hydrologically moving the material into the plant's root zone. At present,
The University of Arizona does not recommend side-dressing of AdmireTM
in lettuce or cole crops.

Growers can expect to obtain 30 to 50 days control of whiteflies using
these recommended techniques with labelled rates. On spring lettuce and
cole crops, AdmireTM has also demonstrated
superior efficacy controlling aphids. Application techniques for aphid
control are similar to those used for fall grown produce. However, keep
in mind that soil-surface banded applications of AdmireTM
require over head sprinkler irrigation for adequate incorporation of the
product. AdmireTM has provided up to
100 days control of green peach aphid, Myzus persicae in lettuce. Although
winged forms may still be found infesting AdmireTM
treated plants, they do not colonize.

Melons (cantaloupes and watermelons):

AdmireTM has a Section 18 emergency
use exemption for use on melons for whitefly control. The current Section
18 for AdmireTM expires June 9, 1996.
As with lettuce and cole crops, AdmireTM
has been shown to effectively control whiteflies when injected at 16 fluid
ounces per acre (80 inch rows) 3.0 inches below the seed line (sub-seed
furrow) just prior to planting. In commercial settings AdmireTM
has been effective at controlling whiteflies when applied through a low
pressure drip irrigation system.

Figure 2. Response of whiteflies on lettuce to sub-surface
and surface band applications of AdmireTM at thinning and heading.

When applying through a drip system, it is important that the emitters
are positioned to deliver the material at the base of the plant to optimize
root uptake. Inject AdmireTM during
a normal irrigation timing and allow the material to uniformly distribute
across to the last emitters before terminating injection. Terminate injection
as soon as the AdmireTM has cleared
the last emmiter.

Because whitefly pressure can be especially intense on fall grown melons,
The University of Arizona does not recommend use of AdmireTM
on melons planted between May 1 and October 1 at elevations below 700
feet without augmenting control with foliar adulticides.

Application Volume

Although little research has been conducted regarding optimal application
volume for maximum AdmireTM activity,
volumes of 5 to 20 gallons per acre have proven effective for sub-seed
furrow applications and 10 to 20 gallons per acre for soil surface banded
applications.

Figure 3. Yield response of lettuce to sub surface and surface
band applications of AdmireTM.

Monitoring Field Performance

Research conducted at The University of Arizona Yuma Valley Agricultural
Center clearly shows the benefits of using sub-seed furrow and surface
banded applications of AdmireTM for
whitefly control in lettuce (Figure 2). The effects of controlling whiteflies
on lettuce correspond closely with increased head weight and diameter
(Figure 3). Additionally, controlling whiteflies on lettuce prevented
the yellowing normally observed on untreated plants. On broccoli and cauliflower,
whitefly control increased yields by preventing delayed crop maturity
and stem "blanching" associated with the presence of whiteflies.

Although AdmireTM has demonstrated
increased yields in lettuce, cole crops and melons through whitefly control,
University of Arizona research has shown that AdmireTM
does not increase yield in the absence of whiteflies. Thus, AdmireTM has no known plant growth regulator qualities.

Immediately after crop emergence, it is not uncommon to find adult whiteflies
and eggs on treated plants, particularly on the cotyledons. This is not
necessarily indicative of an insecticide or application failure, but rather
a delay in uptake of the material. Once the plants reach the one to three
leaf stage, activity should be evident. However, because adults whiteflies
may continually migrate into the field, do not base control on adult densities.
If many adult whiteflies are present on treated plants, look closely around
the base of the plants for adult whitefly cadavers. Also gently tap the
plants against the soil surface and note whether or not the dislodged
adults are alive or dead, and closely check the leaf tissue with a hand
lens for the presence of eggs and immatures. At thinning check the first
couple of basal leaves. University of Arizona research has shown that
plants treated with AdmireTM will generally
have ten or fewer eggs, and five or fewer immatures, while untreated plants
will have 20 to 80 eggs and 30 to 40 immatures (Figure 2). If plants treated
with AdmireTM contain high numbers of
eggs or immatures, alternative control measures should probably be taken.
To date there have been no reported whitefly control failures with AdmireTM.

It is a good idea to maintain a small untreated area in every field treated
with AdmireTM. These areas will provide growers and crop advisors with
a check to evaluate how well the AdmireTM
is performing as the season progresses.

Product Efficacy Management

Because of heavy reliance on AdmireTM
for whitefly and aphid control on vegetables in the lower desert region
of Arizona, sustaining product efficacy is of great concern.

Vegetable crops grown in the low desert area of Arizona where a multi-cropping
system predominates can be categorized for risk of whitefly infestation
on produce and melon crops.

Lettuce and Cole Crops

Low Risk: Crops planted in October or later when temperatures have receded
and there is no significant source (i.e. alfalfa, cotton or melons) of
whiteflies within a one mile radius.

High Risk: Crops planted in September, or later plantings that are near
a significant whitefly source when temperatures are high.

Melons

Low Risk: Melons planted during early spring during cool temperatures.

High Risk: Late spring and fall plantings.

Alternative foliar sprays have proven effective for lettuce, cole crops
and melons under low risk situations. In addition there are several product
management strategies which should help alleviate imidacloprid selection
pressure on whiteflies and maintain product efficacy on vegetable crops.

Consider using foliar materials for whitefly control under low risk
situations.

If possible, avoid using any formulation of imidacloprid (AdmireTM
or ProvadoTM) in cotton.

If by the thinning and heading stages, whiteflies are building up
on fall produce or fall melons, consider applying a non-imidacloprid
foliar material to eliminate possible tolerant individuals.

Avoid using AdmireTM after whitefly
pressure subsides for aphid control in produce scheduled for harvest
before aphid populations traditionally develop.

Palumbo, J. C. and C. A. Sanchez. 1995. Imidacloprid does not enhance
growth and yield in cantaloupes in the absence of whitefly. In: College
of Agriculture, College of Agriculture, 1994 - 1995 Vegetable Report,
pp. 115-121 , Series P-100.

Issued in furtherance of Cooperative Extension work, acts
of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture,
James A. Christenson, Director Cooperative Extension, College of Agriculture
and Life Sciences, The University of Arizona.

The University of Arizona is an equal opportunity, affirmative
action institution. The University does not discriminate on the basis of race,
color, religion, sex, national origin, age, disability, veteran status, or sexual
orientation in its programs and activities.

Any products, services, or organizations that are
mentioned, shown, or indirectly implied in this web document do not imply
endorsement by The University of Arizona.